U.S. patent number 3,623,046 [Application Number 04/871,020] was granted by the patent office on 1971-11-23 for transducer system.
This patent grant is currently assigned to Cox Instruments Division Lynch Corporation. Invention is credited to George Scourtes.
United States Patent |
3,623,046 |
Scourtes |
November 23, 1971 |
TRANSDUCER SYSTEM
Abstract
A circuit for energizing a differential inductor transducer uses
rectifier voltage dividers in a balanced bridge circuit.
Inventors: |
Scourtes; George (Detroit,
MI) |
Assignee: |
Cox Instruments Division Lynch
Corporation (Detroit, MI)
|
Family
ID: |
27051325 |
Appl.
No.: |
04/871,020 |
Filed: |
November 5, 1969 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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494164 |
Oct 5, 1965 |
3528288 |
|
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Current U.S.
Class: |
340/870.35;
73/861.53; 73/861.71 |
Current CPC
Class: |
G01L
9/0026 (20130101); G01F 1/24 (20130101) |
Current International
Class: |
G01F
1/24 (20060101); G01F 1/20 (20060101); G01L
9/00 (20060101); G08c 019/08 () |
Field of
Search: |
;340/199,196,195 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Habecker; Thomas B.
Parent Case Text
This is a division of Ser. No. 494,164, filed Oct. 8, 1965, now
U.S. Pat. No. 3,528,288.
Claims
We claim:
1. In combination with a bidirectional transducer for converting a
varying characteristic of a fluid into mechanical movement having a
support member, first and second series connected flux producing
coils mounted on the support member and an armature member
supported in the flux path of the flux coils and relatively movable
with respect thereto in response to the varying characteristic and
producing a signal, the movement of the armature in one direction
increasing the reluctance of said first coil flux path and
correspondingly decreasing the reluctance of said second coil flux
path, energy means for energizing the first and second coils with a
source of alternating current potential and producing a voltage
drop across each of said first and second coils in accordance with
the position of the armature means, the improvement comprising
first rectifying voltage divider means connected to said energy
means for producing a first unidirectional reference from a first
half wave of the alternating current potential, second rectifying
voltage divider means connected to said energy means for producing
a second unidirectional reference voltage from a second half wave
of the alternating current potential, and means for doubling the
magnitude of the signal comprising the difference in voltage
between the voltage drop across said first coil during the first
half wave and said first reference signal and a second signal
comprising the difference in voltage between the voltage drop
across said second coil during the second half wave and said second
reference signal and indicating means responsive to the successive
first and second doubled signals for indicating the fluid
characteristic.
2. The invention of claim 1 wherein said first and second rectifier
voltage divider means includes first and second series connected
impedance means connected across the source of energy, third
impedance means connected in shunt relation to said first and
second impedance means, and means connected to a point between said
first and second impedance means and variably connected to said
third impedance means for varying the effective ratio of a
combination of said first impedance means and a first preselected
portion of said third impedance means as compared to a combination
of said second impedance means and a second preselected portion of
said third impedance means.
3. In combination with a bidirectional transducer for converting a
varying characteristic of a fluid into mechanical movement having a
support member, first and second series connected flux producing
coils mounted on the support member and an armature member
supported in the flux path of the flux coils and relatively movable
with respect thereto in response to the varying characteristic, the
movement of the armature in one direction increasing the reluctance
of said first coil flux path and correspondingly decreasing the
reluctance of said second coil flux path and the movement of the
armature in an opposite direction decreasing the reluctance of the
first coil flux path and increasing the reluctance of the second
coil flux path, and energy means for energizing the first and
second coils with a source of alternating current potential and
producing a voltage drop across each of said first and second coils
in accordance with the position of the armature means, the
improvement comprising first rectifying voltage divider means
connected to said energy means for producing a first unidirectional
reference from a first half wave of the alternating current
potential, second rectifying voltage divider means connected to
said energy means for producing a second unidirectional reference
voltage from a second half wave of the alternating current
potential, and means for doubling the magnitude of a first signal
comprising the difference in voltage between the voltage drop
across said first coil during the first half wave and said first
reference signal and a second signal comprising the difference in
voltage between the voltage drop across said second coil during the
second half wave and said second reference signal, including first
storage means charged during said first half wave and discharged in
series with said first signal during said second half wave, second
storage means charged during said second half wave and discharged
in series with said first signal during said first half wave,
indicating means responsive to the successive first and second
doubled signals for indicating the fluid characteristic.
4. The invention of claim 3 wherein said first and second rectifier
voltage divider means includes first and second series connected
impedance means connected across the source of energy, third
impedance means connected in shunt relation to said first and
second impedance means, and means connected to a point between said
first and second impedance means and variably connected to said
third impedance means for varying the effective ratio of a
combination of said first impedance means and a first preselected
portion of said third impedance means as compared to a combination
of said second impedance means and a second preselected portion of
said third impedance means.
5. A bidirectional telemetering system for converting a varying
characteristic of a fluid into an indication of the signal
comprising first and second series connected flux producing coils,
an armature member supported in the flux path of the flux coils and
relatively movable with respect thereto in response to the varying
characteristic, the movement of the armature in one direction
increasing the reluctance of said first coil flux path and
correspondingly decreasing the reluctance of said second coil flux
path, energy means for energizing the first and second coils with a
source of alternating current potential and producing a voltage
drop across each of said first and second coils in accordance with
the position of said armature means, the improvement comprising
first rectifying voltage divider means connected to said energy
means for producing a first unidirectional reference from a first
half wave of the alternating current potential, second rectifying
voltage divider means connected to said energy means for producing
a second unidirectional reference voltage from a second half wave
of the alternating current potential, and means for doubling the
magnitude of a first signal comprising the difference in voltage
between the voltage drop across said first coil during the first
half wave and said first reference signal and a second signal
comprising the difference in voltage between the voltage drop
across said second coil during the second half wave and said second
reference signal, and indicating means responsive to the successive
first and second doubled signals for indicating the fluid
characteristic.
6. In combination with a bidirectional telemetering system for
converting a varying characteristic of a fluid into an indication
of the signal comprising first and second series connected flux
producing coils, an armature member supported in the flux path of
the flux coils and relatively movable with respect thereto in
response to the varying characteristic, the movement of the
armature in one direction increasing the reluctance of said first
coil flux path and correspondingly decreasing the reluctance of
said second coil flux path and the movement of the armature in an
opposite direction decreasing the reluctance of the first coil flux
path and increasing the reluctance of the second coil flux path,
energy means for energizing the first and second coils with a
source of alternating current potential and producing a voltage
drop across each of said first and second coils in accordance with
the position of said armature means, the improvement comprising
first rectifying voltage divider means connected to said energy
means for producing a first unidirectional reference from a first
half wave of the alternating current potential, second rectifying
voltage divider means connected to said energy means for producing
a second unidirectional reference voltage from a second half wave
of the alternating current potential, and means for doubling the
magnitude of a first signal comprising the difference in voltage
between the voltage drop across said first coil during the first
half wave and said first reference signal and a second signal
comprising the difference in voltage between the voltage drop
across said second coil during the second half wave and said second
reference signal, including first storage means charged during said
first half wave and discharged in series with said first signal
during said second half wave, second storage means charged during
said second half wave and discharged in series with said first
signal during said first half wave, and indicating means responsive
to the successive first and second doubled signals for indicating
the fluid characteristic.
7. A metering system for indicating the ratio of change of the
impedance of a first and second series connected flux producing
coils, an armature member supported in the flux path of the flux
coils and relatively movable with respect thereto to vary the ratio
of the impedances and energy means for energizing the first and
second coils with a source of alternating current potential and
producing a voltage drop across each of said first and second coils
in accordance with the position of the armature means, the system
comprising first rectifying voltage divider means connected to the
energy means for producing a first unidirectional reference from a
first half wave of the alternating current potential, second
rectifying voltage divider means connected to the energy means for
producing a second unidirectional reference voltage from a second
half wave of the alternating current potential, and means for
doubling the magnitude of a first signal comprising the difference
in voltage between the voltage drop across the first coil during
the first half wave and said first reference signal and a second
signal comprising the difference in voltage between the voltage
drop across the second coil during the second half wave and said
second reference signal, including first storage means charged
during the first half wave and discharged in series with said first
signal during the second half wave, second storage means charged
during the second half wave and discharged in series with said
first signal during the first half wave, and indicating means
responsive to the successive first and second doubled signals for
indicating the fluid characteristic.
8. A metering system for indicating the ratio of change of the
impedances of a first and second series connected flux producing
coils, an armature member supported in the flux path of the flux
coils and relatively movable with respect thereto to vary the ratio
of the impedance, the movement of the armature in one direction
increasing the reluctance of said first coil flux path and
correspondingly decreasing the reluctance of said second coil flux
path and the movement of the armature in an opposite direction
decreasing the reluctance of the first coil flux path and
increasing the reluctance of the second coil flux path, and energy
means for energizing the first and second coils with a source of
alternating current potential and producing a voltage drop across
each of said first and second coils in accordance with the position
of the armature means, the system comprising first rectifying
voltage divider means connected to the energy means for producing a
first unidirectional reference from a first half wave of the
alternating current potential, second rectifying voltage divider
means connected to the energy means for producing a second
unidirectional reference voltage from a second half wave of the
alternating current potential, and means for doubling the magnitude
of a first signal comprising the difference in voltage between the
voltage drop across the first coil during the first half wave and
said first reference signal and a second signal comprising the
difference in voltage between the voltage drop across the second
coil during the second half wave and said second reference signal,
including first storage means charged during the first half wave
and discharged in series with said first signal during the second
half wave, second storage means charged during the second half wave
and discharged in series with said first signal during the first
half wave, said first and second storage means being oppositely
charged during the respective discharge portion of the wave to a
potential equal to the respective first and second signal, and
indicating means responsive to the successive first and second
doubled signals for indicating the fluid characteristic.
Description
This invention generally relates to new and useful improvements in
telemetering systems, and more specifically to improvements in a
transmitting transducer device for changing rate of flow or
pressure into a signal and further to improvements in an electrical
indicating system for producing an output signal in accordance with
the relative movement of an element in a transducer device.
Fluid flow or pressure responsive telemetering systems of the type
to which the present invention is generally directed, have come
into greater widespread use due to increased tolerance requirements
in fluid flow or pressure devices, thus increasing the need for
highly accurate telemetering systems over a wide range of flows or
pressures. Such systems have equal applicability to the flows or
liquids or gases or pressures caused by the pumping of the liquid
or gases.
A similar need has risen in the area of bidirectional flow or
pressure meters wherein the peak amplitude of fluid flows or
pressures in both directions may be accurately measured and
indicated. One such need for a bidirectional telemetering system
including a bidirectional transmitting transducer, involves the
situation of a hydraulic pump and hydraulic motor combination
wherein fluid is pumped into and out of the line by means of a
piston. With the unidirectional metering systems of the prior art,
it has become necessary to convert the motor shaft rotation into a
consistent hydraulic flow, in one direction, by means of a valving
apparatus. Thus, an auxiliary line must be provided for use in
conjunction with the telemetering system, thereby precluding the
use of the telemetering system directly in the pumping line,
Accordingly, it is one object of the present invention to provide a
new and improved telemetering system for indicating the rate of
flow of a fluid or the pressure of a fluid.
It is a further object of the present invention to provide an
improved telemetering system which is responsive to a wide range of
flows or pressures.
It is still a further object of the present invention to provide an
improved telemetering system which is responsive to a wide range of
flows or pressures.
It is still a further object of the present invention to provide an
improved telemetering system which is bidirectionally responsive by
merely reversing a switch.
It is still a further object of the present invention to provide an
improved transducer device for a telemetering system which is
automatically responsive to fluid flows in both directions and is
responsive to pressure, both positive and negative in the latter
case vacuum.
It is another object of the present invention to provide an
improved telemetering system which may be adapted to provide an
output in response to fluid flows or pressures which is a function
of flow or pressure, as for example a logarithmic, linear, or
squared output.
It is still a further object of the present invention to provide an
improved telemetering system having a transducer device which is
free from any rotating parts, such as wheels, or moving ball
bearings.
A further object of the present invention is to provide an improved
transducer mechanism for producing an electrical output signal in
accordance with either the amplitude variations of a bidirectional
flow or pressure or is capable of producing an output signal in
accordance with a fluid flow or pressure in either direction.
It is still a further object of the present invention to provide an
improved transducer device for converting fluid flow or pressure to
an electrical signal which is capable of measuring flow
substantially down to zero and up to a very large flow or
pressure.
It is still a further object of the present invention to provide a
simplified variable orifice, bidirectional transducer device which
is capable of converting fluid flow or pressure to an electrical
signal.
It is still another object of the present invention to provide an
improved transducer device for converting fluid flow or pressure
into an electrical signal, the transducer device being simple to
mount directly in the fluid flow line or directly on a pressure
responsive transducer.
It is still a further object of the present invention to provide an
improved transducer device for converting fluid flow or pressure to
an electrical signal which is effectively centered by means which
varies its force in a substantially linear relationship with the
amount of deflection of an armature member.
It is still a further object of the present invention to provide an
improved fluid flow or pressure to an electrical signal converter
transducer device which is simple to assemble and extremely
accurately radially centered within the bore of the transducer
device.
It is still a further object of the present invention to provide an
improved indicator system.
It is another object of the present invention to provide an
improved indicator system which may be rendered bidirectional by
merely actuating a switch.
It is still a further object of the present invention to provide an
improved indicator system utilizing a voltage doubler rectifier and
incorporating substantially no amplification elements therein.
It is still a further object of the present invention to provide an
improved indicating system wherein a plurality of reference
potentials and a plurality of position sensitive coils are fed from
the same source of electrical energy.
It is still a further object of the present invention to provide an
improved indicating system wherein is provided a simplified
reference voltage zeroing network and a span adjust network, the
system further being provided with a second simplified span adjust
network for flows in the opposite direction or pressures in the
opposite direction from those indicated by said first circuit.
It is still a further object of the present invention to provide an
improved indicating system wherein the difference in voltage
between a change in voltage level of each of a plurality of
position sensitive coils and a reference level is fed to a voltage
doubling circuit.
It is still another object of the present invention to provide an
improved indicator system wherein signal drift in response to
change in electrical characteristics of the system due to
temperature changes and the like, are substantially eliminated.
It is still a further object of the present invention to provide an
improved telemetering system which is inexpensive to manufacture,
reliable in used and substantially impervious to harmful effects
caused by the fluid reacting on the transducer element.
Further objects, features and advantages of the invention will
become apparent from a consideration of the following drawings
wherein:
FIG. 1 is a perspective view illustrating the improved transducer
device installed in flow sensing relation with a fluid carrying
conduit;
FIG. 2 is a cross-sectional view of the transducer device of FIG.
1, with the mounting means removed and illustrating the interior
portion of the transducer device;
FIG. 2a is an elevational view of the diffuser member of FIG.
2;
FIG. 3 is an elevational view of a modified form of the bore and
armature member of FIG. 2;
FIG. 4 is a perspective view illustrating a pressure responsive
transducer device incorporating certain principles of the present
invention;
FIG. 5 is a cross-sectional view of a further pressure responsive
transducer device and illustrating the interior features thereof;
and
FIG. 6 is a schematic diagram of an indicating system incorporating
certain other principles of the invention, the indicating system
being capable of being utilized with any form of transducer device,
including those illustrated in FIGS. 1 to 5.
Referring now to the drawings, particularly to FIGS. 1 and 2, a
telemetering system incorporating the principles of the present
invention is illustrated wherein a flow or pressure transmitting
transducer 10 may be incorporated directly into the line by means
of a coupling mechanism 12. The coupling mechanism 12 generally
comprises a pair of concentrically counterbored plates 14, 16 which
are positioned on each end of the flow or pressure line 18 in
face-opposing relation with each other, whereby the counterbored
portions are in axial alignment with the axis of the pressure or
fluid flow lines 18. The two face-opposing, counterbored and plate
members 12 provide a space into which the transducer device 10 may
be inserted. Each of the end plates 14, 16 and each end of the
transducer device 10 have a pair of mating faces formed thereon
which are capable of being brought into sealing engagement with of
the through suitable gasket means disposed between the opposing
faces. Thus, a leakproof seal is provided between the fluid flow
line 18 and the transducer device 10. A plurality of fastener
members 22, representatively illustrated as nut-bolt assemblies,
are provided on the outer periphery of each of the end plate
members 14, 16 whereby the tightening of the fastener assemblies 22
brings the mating faces into sealing engagement with each other. It
is to be understood that the opposing faces of plates 14, 16 may be
made relatively flat, without a counterbored portion, and the bolts
22 utilized to center the transducer 10 on the plates 14, 16.
Similarly, other forms of connection to the line 18, as will be
discussed in conjunction with the detailed description of FIG. 2,
may be utilized in connecting the transducer 10 to the pressurized
line 18.
The transducer assembly itself generally comprises an outer housing
or shroud member 28 formed of magnetic material, which is adapted
to surround a monmagnetic body portion 30 having a pair of
peripheral grooves 32 formed therein which are adapted to receive a
pair of circularly induction wound coils 34, 36. The interior of
the body portion 30 is formed with a bore 40 which is adapted to
receive an armature assembly 42 therein. The armature assembly 42
generally comprises a pair of end member 44, 46 which are suitably
positioned at either end of the body portion and serve as diffusers
to break up any flow pattern which may be present in the flow of
fluid through the fluid line 18. The two diffusers 44, 46 or end
members may be formed of magnetic or nonmagnetic material and are
interconnected by a nonmagnetic shaft member 50 having an armature
member 52 slidably retained thereon. The armature member 52 is
positioned in the axial center of the bore 40 by a pair of opposing
spring members 56, 58 which are adapted to engage the armature
member 52 at one end thereof and the diffuser members 44, 46 at the
respective other ends. The armature member 52 is formed with a pair
of peripheral guide portions or pilots 60, 62 as are the diffuser
members formed with like circumferential guide portions or pilots
64, 66 to suitably support the spring members 56, 58. Thus, the
armature member 52 is effectively centered on the shaft 50 between
the two diffusers 44, 46 and is capable of being slidably displaced
on the shaft, in one direction or other, by means of fluid flowing
in one or the other direction. It will be noted that the spring
members 56, 58 are positioned between the end member 100 and
armature 52, and armature 52 and end member 102 such that the
effective forces of the springs are opposing each other to increase
the effective spring rate of the combination of springs 56, 58. For
example, in linear springs having equal springs rates, the
effective spring rate of the combination of springs 56, 58 is
doubled. The initial force or preload on the armature at zero flow
ore pressure conditions is essentially zero. Thus, the range of the
transducer device is greatly increased over conventional
transducers.
The shroud member 28 is provided with a nipple assembly 70 which is
adapted to house a plurality of connections to the coils formed in
the grooves of the body member. The nipple assembly generally
includes an annular shaped body portion 72 which may be integrally
formed or cast with the shroud member 28 or suitably attached
thereto, as by welding. The interior of the body portion 72 is in
communication with the grooves 32 formed in the body member 30,
thereby facilitating the positioning of a pair of leads 72 therein.
A support member 78 is attached to the body portion 72, as by
screws to form terminals for the leads 74. A connector member 80 is
threaded or otherwise fastened to the body portion and provides
protection for the cable connection to a suitable electrical
indicating apparatus. The coils 34, 36 are normally in series,
whereby the magnetic flux produced by energization of the coils 34,
36 will flow through the body member 30, through the magnetic
armature member 52 to the diffuser member 44 in the case of
magnetic diffuser 44, and back to the respective end of the
magnetic shroud member 28.
As stated above, diffuser members 44, 46 may be chosen to be
fabricated of magnetic or nonmagnetic material. In the case where
the diffuser is formed of magnetic material, the flux path from the
coils 34, 36 will be through the diffuser members 44, 46 as a low
reluctance path. In this situation, the movement of the armature
member varies the reluctance of the flux path approximately as a
square function of the position of the armature. However, in the
case where the end members 44, 46 are formed of nonmagnetic
material, the output signal from coils 34, 36 will vary as a linear
function of the position of the armature 52. In this latter case,
the flux path will be through the radial gap between the hub end of
the armature member and the body portion 30.
It is to be noted that the movement of the armature member 52 on
the shaft 50 due to the increase or decrease of flow through the
bore 40 will increase or decrease the gap between the armature
member 52 an the respective diffuser or end member 44 thereby
increasing or decreasing the reluctance of the magnetic path for
the flux produced by the coil. The second coil 36 has a similar
path through the left portion of the shroud member 28, the body
member 30 at the left portion thereof, the diffuser member 46 in
the case of a magnetic diffuser, the variable air gap to the
armature member and back to the shroud member. In the case where
the diffuser is nonmagnetic, the flux path will be through the gap
between the hub 81 of the armature member 52, as described above.
It is to be noted that the change in air gap due to the movement of
the armature member in one direction, will increase the reluctance
of one of the coils while at the same time decreasing the
reluctance of the flux path of the other coil. Thus the impedance
of one coil is increased linearly while the impedance of the
opposite coil is decreased linearly by a corresponding amount.
The interior of the bore has been formed with a constructed flow
area portion 82 which is in mating engagement with a circular knife
edge 84 formed on the armature member 52. At zero flow, the
armature is effectively centered with the knife edge 84 on the
armature contiguous to the reduced flow area portion 82 of the
bore. The knife edge on the armature member is formed by removing
portions of the body of the armature member in a particular
configuration or by molding the bore 40 in the desired
configuration. In the representative example illustrated, the bore
is shown to be decreasing linearly, however, it is to be understood
that any configuration may be utilized to produce a desired
output.
For example, an exponential curve or an exponentially decreasing
and increasing flow area will react with the flow to produce an
output in the indicating system which is substantially linear. On
the other hand if a linear decreasing and increasing flow area is
utilized, the output at the indicating device will be substantially
logarithmic. Also, in the event a smooth bore is utilized, the
output will vary as a square function of the flow. Similarly, the
armature member has material removed from an outer portion thereof
to form the knife edge 82, and this material may be removed in a
plurality of configurations. For example, the surfaces 86, 88 may
be formed in a straight or linear configuration, as illustrated in
FIG. 2 of the drawings, or an exponential configuration, as
illustrated in the modified form 90 of the armature shown in FIG.
3. Thus with an increase of flow, the flow orifice through which
the fluid is flowing will vary in either a linear or exponential
fashion to produce a logarithmic or linear output, respectively, or
as a square output in the case of a smooth bore. The configuration
of both the armature member and the bore is symmetrical about the
zero flow point thereby providing a bidirectional indicating
device. The flow in one direction will enter the transducer from
the right through the apertures 92 formed in the diffuser 44 to
impinge on the right face of the armature 52. The flow then travels
through the remainder of the bore 40 after moving the armature 52
to the left, and exits from the transducer 10 through apertures 94
formed in the diffuser 46.
Referring specifically to FIG. 3, it is seen that the bore 40 is
formed as a smooth cylinder and a variable orifice means 91
inserted therein having a pair of elongated portions 93, 95 which
are adapted to closely fit the interior diameter of the bore 40 to
retain the member 91 therein. A central portion is formed with a
flow constricting swagged portion 97 to vary the deflection of the
armature 90 in accordance with a particular function of flow.
In FIG. 2, armature member assembly 42 is accurately radially
positioned in the bore 40 by means of an annular, inwardly facing
pair of counterbores 96, 98 formed on the inner surface of the body
member 30. The counterbores 96, 98 are accurately formed
concentrically with respect to the axis of the bore thus
positioning the center of the diffusers 44, 46 on the axis of the
bore. The diffusers 44, 46 include a central hub portion 100, 102
which are formed with counterbored apertures 104, 106 concentric
with the outer periphery of the diffusers 44, 46. The inside
diameter of the apertures 104, 106 closely approximate the outside
diameter of the shaft 50 thereby forming a close fit therebetween.
The hub portions 100, 102 are provided with internally threaded
bores which are adapted to threadedly engage mating threaded ends
of the shaft 50. In assembling the armature assembly 42, one
diffuser is threaded on the shaft 50 and the first spring, the
armature and then the second spring are successively placed on the
shaft 50 in the order shown and described. The armature assembly
thus formed is then inserted into the bore from on end and the
remaining diffuser is threaded onto the shaft from the other end of
the bore 40. The diffuser is continuously threaded until the
diffusers are inserted into the counterbores 96, 98 and in binding
engagement with the shoulders formed in the bore 40. The binding
force is sufficient to retain the armature assembly 42 in the bore
40.
As stated above, the mounting assembly 12 may take other forms
suitable for use in pressurized lines, such as line 18. One such
form includes removing the diffuser members 44, 46 from from the
counterbored portions 96, 98 and forming interior threads on
counterbores 96, 98. An elongated diffuser nipple member formed of
solid cylindrical, or stepped stock, is then threaded into portions
96, 98 by means of exterior threads formed therein, and a portion
of the diffusers may project beyond the body member 30. The
diffuser nipples may then be counterbored at the exterior ends
thereof and threaded to receive the threaded end of the pipe 18 and
a diffuser may be formed by drilling through the portion of the
nipple which has not been counterbored. Thus the pipe, diffusers
and bore 40 are properly aligned. A second modification may take
the form of a flange fitting wherein a solid stock is similarly
formed in a nipple fitting, as described above. For example, a
solid, stepped generally cylindrical stock has a first end threaded
on an exterior surface thereof to threadedly engage mating threads
formed on the interior of portions 96, 98. The portion of the
cylinder adjacent the threaded portion may have a larger exterior
diameter than the threaded portion and is adapted to slidably
receive a radially extending flange member thereon. The outer end
of the nipple is formed with a still larger diameter portion to
retain the flange on the nipple and the flange may be counterbored
to receive the head portion. The head portion is adapted to coact
with the body portion to retain the flange in position and also to
provide strength to the flange member when it is mated with a
second flange member on the pressurized pipe. The threads on the
interior surface of the counterbored portion are omitted in this
situation due to the fact that the end of the pipe is not
threaded.
As stated above, the invention incorporated herein is not
restricted to flow type of transducer devices but also may be made
to include pressure responsive transducers including systems
wherein a means is provided for transforming pressure into linear
movement, the linear movement being connected to a second
transducer device which is cable of transforming the mechanical
movement into an electrical signal. In one form, the general
configuration of the first transducer may take the form of a
Bourdon tube, or any form of pressure responsive device, and the
second transducer may take a form which is substantially identical
to that described in conjunction with the flow type of transducer.
However, in pressure responsive type transducer, the armature
member may be fixed relative to a shaft, the shaft being slidably
mounted in a pair of end members which are suitably mounted in the
bore in either end of the body member and concentric with the bore,
or may be slidable mounted on a fixed shaft, as described in
conjunction with FIG. 2.
Referring now to FIGS. 4 and 5, there is illustrated one preferred
embodiment of a pressure responsive transducer assembly 110 which
may be utilized with the indicator system illustrated in FIGS. 6.
Referring first to FIG. 5 and as described in conjunction with the
flow situation, a body member 112 is provided with a pair of
concentrically wound coils 114, 116 which set up a pair of flux
paths through an armature member 118 and end members 120, 122
whereby the movement of the armature member increases the
reluctance of one path and decreases the reluctance of the opposite
path, as was the case with the fluid responsive transducer assembly
10. It is to be noted that end members 120, 122 may be formed of
magnetic or nonmagnetic material in accordance with the desired
output results. Accordingly, the impedance of the above mentioned
coils is varied in accordance with the position of the armature
within the bore. A pair of opposing centering springs 128, 130 are
provided to initially position the armature within the bore, thus
zeroing the armature 118 within the transducer device 110.
The output of the transducer device is fed through a nipple
assembly 134 attached to the outer periphery of a shroud member 136
and includes a plurality of conductors 138, 140 in electrical
communication with the coils 114, 116 formed in the body member
112. The induction coils 114, 116 are connected in series across a
suitable source of alternating current potential and the voltage
drop across each of the coils varies in accordance with the change
of reluctance of the respective magnetic paths due to the change in
position of the armature member in the bore of the body response to
a variation in pressure. Accordingly, for an given voltage drop or
voltage supplied to the coils, the total voltage drop will be
proportioned across each of the coils in accordance with the
reluctance of the respective magnetic paths thereby providing an
indication of the relative position of the armature member within
the bore.
In the modification illustrated in FIG. 5, the armature 118 is
slidably supported relative to shaft 142 and the shaft is
relatively fixed with respect to the end members 120, 122. A
cylindrical portion of friction material may be positioned to form
retaining members 144, 146, to facilitate the assembly of shaft 142
within end members 120, 122 or end members 120, 122 may be
threadedly fixed to the shaft 142, as in the case of FIG. 2. The
end members are radially positioned within the bore 150 of the body
member 112 by means of concentric grooves 152, 154 formed therein
as described in conjunction with FIGS. 1 to 3. The end members 120,
122 are fixed in the grooves by suitable snaprings 156, 158 or any
other fastening means, or merely by the threaded engagement between
end members 120, 122 and shaft 142. The transducer The transducer
of FIG. 5 is particularly adapted to measure pressure drops across
a valving member, orifice or the like wherein one face of the
transducer 110 is suitably connected to a tube which is in fluid
communication with the pressurized portion on one side of the
valve, etc. while the other face of the transducer is connected to
a tube which is in fluid communication with the other side of the
valve, etc. The connection may be made in any suitable manner, as
for example, with the connectors described above. As an alternative
arrangement, the retaining members 144, 146 may be formed of a
relatively frictionless bearing material to permit the shaft 142 to
be freely slidable therein. In this situation, the armature member
is fixed relative to the shaft 142 and the shaft-armature assembly
is axially shifted in response to an increase or decrease in
pressure.
Referring particularly to FIG. 4, a pressure responsive transducer
device is illustrated as being connected in pressure responsive
relation to a Bourdon tube of pressure responder. It is to be
understood that while the subject invention is illustrated and
described in conjunction with the Bourdon tube type responder, any
type of pressure responder may be utilized to linearly actuate the
shaft member 142. Thus, any type of transducer device which is
capable of transforming bidirectional or unidirectional pressure
into a linear motion may be utilized to actuate the shaft 142. It
is to be understood that pressure is used generically to include
both a positive and negative pressure, a pressure or vacuum,
respectively.
The responder 170 generally comprises a tubular member 172 which is
adapted to be attached to a line, the pressure of which is to be
measured by means of a connector assembly 174. The other end of the
tubular member 172 is interconnected with stand assembly by means
of a rigid fitting assembly 176 wherein the coupling 174 and
fitting assembly 176 may take any form common in the art. The upper
end of the rigid fitting assembly 176 is provided with a
conventional Bourdon tube 180, which is generally of a "C"
configuration having one end fixed to a block portion 182 forming a
part of the stand assembly 176, and the other end 184 thereof,
being interconnected with the longitudinally movable shaft 142
through a fixed linkage assembly 188. The Bourdon tube is of a type
wherein the end 184 is moved outwardly of the transducer device 110
as the pressure increases and moves inwardly toward the transducer
110 as the pressure decreases. Similarly, in a vacuum situation,
the greater the vacuum the more the displacement of the end 184
toward the transducer device 110.
Accordingly, the shaft member 142 is moved inwardly and outwardly
with a decrease and increase in pressure, respectively, to thereby
change the relative reluctance of the induction coils 114, 116
contained within the transducer device 110. The linkage assembly
maybe of any type, and is representatively illustrated as
comprising a plate member 190 which is welded or otherwise rigidly
fastened to the end 184 of tube 180 and a central portion of the
plate member 190 is similarly welded or otherwise fixed to the end
of the elongated shaft 142. Accordingly, the up and down motion of
the end 184 is transmitted to the shaft member 142 through the
linkage assembly 188. The interior of the transducer 110 may take a
similar form to that illustrated in FIG. 5 with the exception that
the springs 126, 130 and the end members 120, 122 are eliminated to
reduce the opposition to the movement of shaft 142. Also, armature
member 118 is fixed relative to shaft 142 and shaft 142 is extended
at one end thereof to permit the attachment of the linkage assembly
188. In the situation where a large force is developed for a given
change in pressure, it may be desirable to retain springs 128, 130
and end members 120, 122 to increase the range of the transducer
110.
While certain prior art systems utilize circuitry which is capable
of measuring the variation of impedance of a position sensing
winding. The indication system of the present invention
incorporates a sensing circuit which provides an output signal in
accordance with the ratio of impedances of the plurality of
windings on the body member. Thus, a variation in impedance of the
sensing coils in response to temperature change and the like, will
not vary the output signal indicative of the position of the
armature within the bore. Also, the indication system of the
present invention utilizes a rectified voltage doubler circuit
which provides the measuring art with a highly responsive direct
current signal derived from an alternating current source, the
direct current signal being of sufficient magnitude to actuate an
indicating device, as for example a galvanometer, or the like.
Referring now to FIG. 6, there is illustrated a representative
embodiment of an indicating circuit which is adapted to be utilized
in conjunction with the transducer device described in conjunction
with FIGS. 1 to 5. Particularly, the indicating circuit is provided
with an input source of power by means of a plug 202 which is
adapted to be interconnected with a suitable source of alternating
current, as for example, 115 volt AC. The plug is connected through
a pair of switches 204, 206 to a constant voltage or voltage
regulated transformer 208, which includes a primary winding 210, a
secondary winding 212 and a core member 214. The transformer 208
may be of the type such as that sold under the trade name "Sola
Transformer."
The output of the transformer 208 is fed through a pair of
conductors 218, 220 to a transducer circuit 222, the transducer
circuit consisting of a pair of series connected inductor windings
224, 226. The inductor windings 224, 226 correspond to the windings
34, 36 of FIG. 2 or 114, 116 of FIG. 5, and both windings are
chosen to have generally the same electrical and magnetic
characteristics. The windings 224, 226 are magnetically coupled to
a magnetic armature member 230 which is positioned in flux coupling
relation to both of the windings 224, 226. The magnetic member 230
is a schematic representation of the variable magnetic circuit of
FIGS 2 and 5 caused by the bidirectional movement of the armature
52 and 118, respectively. The armature 230 is adapted to moved
linearly in a direction parallel to the axis of the coils 224, 226.
Accordingly, when the armature member 230 is moved downwardly, the
impedance of the winding 224 is lowered and the impedance of the
winding 226 is corresponding raised.
It is to be noted that a constant voltage impress across conductors
218, 220, thereby presenting a constant voltage across the series
combination of the windings 224, 226. Thus, the drop across each of
the windings 224, 226 will be a proportionate share of the total
voltage present across conductors 216, 220, and is representative
of the relative movement of the armature member 230 across the
magnetic path of each of the windings. The voltage across
conductors 218, 220 is also fed to a first balanced voltage divider
circuit 234, utilized when the voltage at conductor 218 is positive
with respect to conductor 220, a second balanced voltage divider
circuit 236, which is adapted to be utilized when the voltage at
conductor 218 is negative with respect to be utilized when the
voltage at conductor 218 is negative with respect to conductor 220,
and a voltage doubler bridge circuit 240, which is adapted to
provide an indication of the flow or pressure within the
system.
The balanced voltage divider circuit 234 includes provisions for
varying the output voltage thereof in such a manner such that the
voltage across conductors 218 and 220 is exactly halved at the
output terminal thereof. Similarly, the second balanced voltage
divider circuit 236 also includes provisions for diving the voltage
between conductors 218, 220 and presenting this divided voltage as
an output signal. The voltage doubler bridge circuit 240 includes
means for reversing the polarity of the indicating circuit and also
further includes means for adjusting the span of the indicating
device contained therein to provide a full scale deflection at the
maximum flow of pressure which is anticipated.
Referring to the first balanced voltage divider circuit 234, the
voltage across conductors 218, 220 is fed through a diode 250, a
first relatively low impedance resistor 252, a second relatively
low impedance resistor 254, and a second diode 256 all connected in
series between conductors 218 and 220. A variable impedance,
potentiometer circuit is connected across the series combination of
resistors 252, 254 and generally comprises a slider 268, a
potentiometer arm resistor 260 and a potentiometer resistor 262. In
the circuit of the present invention, it is desired to provide a
voltage at a node 264 between resistors 252 and 254 which is half
the voltage between conductors 218 and 220. Accordingly, the slider
potentiometer, including resistors 260, 262, may be varied to vary
the upper portion of resistor 262 as compared to the combination of
resistors 254, 260 and the lower portion of 262. Thus, the voltage
at node 264 may be varied by varying the position of the slider 268
with respect to the resistor 262.
The second balanced voltage divider circuit 236 is similarly
connected with a pair of diodes 270, 272 connected in series with a
pair of resistors 274, 276, the resistors 274, 276 and diodes 270,
272 being connected across the conductors 218, 220. The second
voltage divider circuit has been illustrated with fixed resistors
274, 276 to set the voltage at a node 290 with respect to the
conductor 220. Accordingly, the voltage divider circuit 234, and
particularly the zero resistor 262 is utilized to balance the
voltage at node 264 to that of node 290. However, a second
balancing or zero circuit may be incorporated into divider circuit
236 to provide additional adjustment of the voltage at nodes 264,
290. Accordingly, the voltage at node 290 will be approximately
half the voltage across conductors 218 and 220.
The output voltages at nodes 264 and 290 are fed to opposite points
of the bridge circuit 240 and a center tap conductor 294 is
connected to an upper node 296 of the bridge 240, the other end of
which being connected to a node 292 between the inductors 224 and
226. A first capacitor 300 is connected between nodes 264 and 296
and a second capacitor 302 is connected between nodes 290 and 296.
Thus voltage across capacitors 300 and 302 will vary in accordance
with the difference in potential between the voltage at nodes 264
and 296 in the case of capacitor 300 and the difference in voltage
between nodes 290 and 296 in the case of capacitor 302, as will be
more fully explained in conjunction with the description of the
operation of the circuit.
A galvanometer type indicating device 306 is connected at one end
thereof to a first reversing switch 308 and through a variable span
impedance 310 to the node 264 and the other end of the indicating
device 306 is connected to node 290 through a second reversing
switch 314 and a conductor 316. The span impedance 310 is made
variable to vary the amount of current being fed to the indicating
device to provide a full scale deflection for the maximum amount of
flow or pressure which is anticipated, thereby providing a
calibration means for the indicating device in accordance with the
anticipated rating of the system.
With the reversing switches 308, 314 in the opposite direction, or
poled opposite to that shown, a circuit is completed from node 290
through a second span variable resistor 320, a terminal 322, the
arm of reversing switch 308, the indicating device 306, to the arm
of the second reversing switch 314. With the arm of the reversing
switch 314 in the opposite position, that is in contact with a
second terminal 324, the indicating device 306 is connected to the
node 264 through a conductor 328. Each of the resistors 310 and 320
have been provided with a sliding arm 330, 332 to vary the
impedances of the resistors 310, 320 and also a pair of diodes 334,
336 have been connected in oppositely poled, shunt relation to the
indicating device 306 to provide protection for the indicating
device 306.
In operation and assuming that the reversing switches 308, 314 are
in the position shown, the system is initially calibrated with zero
flow through the meter. It is further 44 assumed that the armature
230 has been exactly centered between the inductors 22 4 and 226 at
a no-flow condition. Accordingly, the switches 204 and 206 are
closed, thus applying a voltage between conductors 218 and 220 and
for purposes of example, it is assumed that the voltage across
conductors 218, 220 has been lowered to approximately 6-volts,
alternating current, due to the step down transformer 208. For
purposes of simplicity, the conversion between alternating current
and direct current will be assumed to be equal and the 3-volt volt
direct current potential at the nodes 264, 290 is assumed to be
one-half of the potential across the conductors 218, 220.
Accordingly, a 6 volt potential is impressed across conductors 218,
220 and accordingly across the series combination of the diodes
250, 256 and the balanced voltage divider circuit 234 and similarly
the series combination of diodes 270, 272 and the balanced voltage
divider 236. It is to be understood that the voltage divider
circuit 234 is utilized during what is assumed to be the positive
half cycle or wherein conductor 218 is positive with respect to the
conductor 220, and the voltage divider circuit 236 is utilized
during the corresponding negative half cycle or when conductor 220
is positive as compared to conductor 218. Accordingly, with zero
current flow through the meter, thereby permitting armature 230 to
assume the null or zero position, the meter 306 should read zero
due to the fact that the average pulsating DC voltage at a node 264
is approximately 3-volts and the average pulsating DC voltage at
node 290 is also approximately 3-volts. However, it is important to
note that the voltages at nodes 264 and 240 are identical. If these
voltages are not identical, the slider 268 may be correspondingly
adjusted to vary the voltage at node 264 to thereby zero the meter
indicating device 306.
With the circuit initially at rest and with the balanced voltage
divider circuit circuit 234 adjusted to the half way position
wherein the voltages at nodes 264 and 290 are exactly equal, the
switches 204 and 206 are closed, thereby permitting the first half
wave to flow through the circuit,. Accordingly, the upper end of
inductor winding 224 is positive with respect to the center tap
node 292 and the node 292 is positive with respect to the conductor
220, assuming that the armature device 230 has been sufficiently
lowered to cause the lower inductor 226 to drop twice the amount of
voltage available between conductors 218 and 220 as compared to the
voltage dropped across inductor 224. Accordingly, the voltage
across inductor 226 will be approximately 4 volts while the voltage
across inductor 224 will be approximately 2 volts. The center tap
voltage at node 292 will be at approximately 4 as compared to the
6-volts at conductor 218 when measured from conductor 220, and this
4-volt potential will be fed to node 296.
It has already been stated that the voltage at node 264 is at
3-volts thereby providing a 1-volt drop across capacitor 300 to
charge the capacitor plus to minus in a direction between nodes 264
and 296 in accordance with the upper polarity illustrated in
parenthesis on the drawing. The same 4-volt potential applied at
node 296 is applied cross capacitor 302. However, the diodes 270,
272 are back biased to preclude the charging of capacitor 302.
However, on the second half cycle, the negative half cycle, the
diodes 270 and 272 will be forwarded biased to establish a 3-volt
potential at node 290 and the voltage at node 296 will assume a
4-volt potential with respect to the positive conductor 220.
Accordingly, the 4-volt potential at node 292 is fed by means of
conductor 294 to the node 296, and with the node 290 at 3-volt
potential, the capacitor 302 will be charged to 1-volt, with the
upper polarity illustrated in the drawing. Accordingly, the
capacitors 300, 302 are charged at 1 volt each, in accordance with
the polarity illustrated, by the first full wave cycle impressed on
conductors 218, 220.
As is seen from the foregoing description, each of the capacitors
300, 302 is charged with the differences between the voltage at
node 296 and each of nodes 264, 290. Accordingly, the sum of the
voltages across capacitors 300, 302 is impressed across the meter
306 to provide an output reading which is indicative of the charge
on the capacitors. It will be noted that the net voltage across the
meter 306 is double the difference signal, thus providing the
voltage doubling effect. The particular parameters chosen for each
charging circuit are typically of a low impedance to provide the
full difference signal across the capacitors. Contrariwise, the
discharge circuit through the meter is of a high impedance to
maintain a substantial portion of the charge on the capacitors, and
any discharging will be resupplied on a subsequent cycle. In this
way, the capacitors act as a transfer agent for the charge from the
coils to the meter.
When the second positive half cycle is impressed on conductors 218,
220, the voltage at node 292 will again rise to a 4-volt potential
as compared to the potential at conductor 220, this 4-volt
potential being fed by conductor 294 to the node 296. Accordingly,
with a 4-volt potential at node 202 and with the capacitor 302
charge negative to positive between nodes 290 and 296, current will
flow from node 264, through resistor 310, slider 330 combination,
reversing switch 308, indicating device 306, reversing switch 314,
conductor 316, node 290, through a second 1-volt potential across
capacitor 302 to node 296. It will be noted that upon the discharge
of capacitor 302 due to the flow of current in the opposite
direction through the capacitor, the capacitor 302 gives up its
charge to provide the second volt potential, and the capacitor 302
is charged in an opposite direction, or plus to minus as current
flows from node 290 to 296. This polarity is illustrated in
parenthesis in the drawing. According, a 2-volt potential has been
impressed across indicating meter 306, the 2-volt potential being
double the difference between input nodes 296 and 264.
On the negative half cycle, the conductor 220 becomes positive and
node 202 assumes a 4 -volt potential, the 4 -volt potential being
fed to node 296 by means of conductor 294. With the 4 -volt
potential at node 296, current will flow from node 296 through
capacitor 300, which is charged minus to plus, to add an additional
volt to the signal, through node 264, resistor-slider arm
combination 330, 310, reversing switch 308, indicating device 306,
reversing switch 314, conductor 316 to node 290, which is at a 3
-volt potential or 1 -volt less than the potential at node 296.
Accordingly, a second 2 -volt potential is presented to indicating
device 306 and the current flow therethrough is in the same
direction as was the current flow through the indicating device
during the positive half cycle. This operation is continued thereby
giving a constant output indication at meter 306 until such time as
the armature 230 is moved to a new position.
It will be noted from the above discussion that each cycle of
current flow is through resistor 310, slider arm 330 combination.
Accordingly, the maximum flow, which is desired to be measured by
the system illustrated, may be passed through or the maximum
pressure may be impressed on the transducer device 222, thereby
moving the slug or armature 230 to its maximum deflection position.
Accordingly, with maximum flow or pressure being impressed on the
armature member 230, the effective resistance presented by resistor
310, slider 330 combination to the flow of current through the
meter may be adjusted such that the meter will provide maximum
deflection for maximum movement of the armature member 230.
Accordingly, if the meter is reading below the maximum, the
effective resistance of the span resistor 310 may be decreased and
contrariwise, if the meter is reading high, the effective
resistance of the span resistor 310 may be increased.
As was stated above, the reversing switches 310, 314 have been
provided in the event a reverse flow or pressure is impressed on
the armature device 230. Accordingly, if the armature is moved in a
direction opposite to that described above, the switches 308, 314
are reversed whereby the armatures are in contact with the
terminals 322 and 324. In the event it is desired to calibrate the
indicating circuit in the reverse direction, the reversing switches
are switched into contact with terminals 322 and 324 and the
effective resistance of the span resistor 320 is adjusted to give
maximum flow of maximum deflection of the meter 306 for maximum
movement of the armature member 230. It will be noted that the
current will flow through the meter in the same direction for the
opposite flow or pressure in the same direction as did current flow
through the meter 306 in the direction described above.
While it will be apparent that the preferred embodiments of the
invention disclosed are well calculated to fulfill the objects
above stated, it will be appreciated that the invention is
susceptible to modification, variation and change without departing
from the proper scope or fair meaning of the subjoined claims.
* * * * *